The spacecraft Cassini has taken a dazzling series of photos of Saturn as it nears the end of its seven-year, 2bn-mile journey to one of the solar system's strangest planets.

Cassini is one of the largest spacecraft built. It set off in 1997, looping around the sun twice before it gained speed for its journey towards the Saturnian system.

On May 18, Cassini will begin to feel the gravitational tug of the giant gaseous planet with famous rings and at least 31 moons. On June 11 it will pass within 1,200 miles of Saturn's tiny moon Phoebe.

On July 1, it will slow down, fly through one of the dark bands that separate the rings and become one of the planet's satellites.

On Christmas Day, it will drop the European Space Agency's probe Huygens on a 22-day journey towards a spectacular suicide dive into Titan, a mysterious moon that may have lakes or even seas of freezing methane and ethane. Altogether Cassini will make 74 orbits of the ringed planet, make 44 fly-bys of Titan, and survey Hyperion, Dione, Rhea and Iapetus.

Its first target is the planet itself, and the ring system of billions of orbiting lumps of rock and ice. In February when Cassini took the shots that make up this image, Saturn was less than half the distance from Earth to the sun.

The smallest features visible are about 330 miles across, but astronomers can see the reflected light from the icy moon Enceladus - 323 miles across.

Saturn's own shadow obscures part of the rings but differences are starting to become clear. The outer ring is comparatively translucent, the centre ring seems to form a bright, banded reflecting disc and the innermost ring has begun to take diaphanous shape. The contrast in the picture has been very slightly enhanced by Nasa.

Carolyn Porco, leader of the Cassini camera imaging team at the University of Colorado, Boulder, said: "It's been 13 years in the making, and it is one spectacular ride from here."

· The £600m European Rosetta - destined to begin a 10-year journey to go into orbit around a comet - remained grounded yesterday at Kourou in French Guiana after insulating foam fell from the rocket to lift it into space.